The present disclosure relates to orthopedic implants and, in particular, relates to spinal implants.
Described herein are embodiments and methods for securing a bone stabilizer assembly. Some embodiments provide a coupling member assembly, for securing a pedicle screw to a retention rod, the assembly including a coupling member having two opposed threaded internal surfaces and a locking member first portion and a compression nut configured to be received by the coupling member and to threadingly engage the coupling member threaded internal surfaces, the compression nut having a locking member second portion. In some embodiments, the coupling member and the compression nut are configured to engage each other via the locking member first and second portions such that relative rotation between the coupling member and compression nut is limited without deflection of the opposed threaded internal surfaces relative to each other.
In some embodiments, the locking member first portion comprises a recess in the internal bore, the recess having a greater cross-sectional dimension than a greatest cross-sectional dimension of the threaded internal surfaces. Some embodiments provide that the locking member first portion comprises a lip having a cross-sectional dimension less than the cross-sectional dimension of the recess, and the locking member second portion is configured to engage the lip and thereby deflect the two opposed threaded internal surfaces relative to each other as the compression nut is received by the coupling member.
In some embodiments, the locking member second portion comprises a flange on the compression nut, the flange having a greater cross-sectional dimension than a greatest cross-section dimension of the threaded internal surfaces of the coupling member. In some embodiments, the locking member first portion comprises a lip that interlocks with a portion of the flange to prevent withdrawal of the compression nut from the coupling member.
Some embodiments provide that the locking member first and second portions comprise sawtooth edges that interlock to limit relative rotational movement between the compression nut and the coupling member without deflection of the two opposed threaded internal surfaces. In some embodiments, the locking member first and second portions comprise a plurality of detents that limit relative rotation between the compression nut and the coupling member.
In some embodiments, the locking member first portion comprises a tapered surface that is configured to deflect the two opposed threaded internal surfaces by engagement with a portion of the compression nut as the compression nut is received by the coupling member. Some embodiments provide that the locking member second portion comprises a tapered surface that is configured to deflect the two opposed threaded internal surfaces by engagement with a portion of the coupling member as the compression nut is received by the coupling member.
Some methods include providing a fixation member configured to engage a bone and having a head portion and shank portion. Some methods also include providing a coupling member having an internal bore sized to receive the shank portion of the fixation element and a seat configured to support the head portion of the fixation element, the coupling member further adapted to receive a stabilizer rod, the internal bore having two opposed threaded internal surfaces and a locking member first portion. In some methods, a compression nut is provided that is configured to be rotatingly received by the coupling member and to threadingly engage the coupling member threaded internal surfaces, the compression nut having a locking member second portion, the compression nut configured to translate a force to the head portion through the rod such that the head portion is forced against the seat of the coupling member to limit relative movement between the fixation element and the coupling member. Some methods include engaging the coupling member and the compression nut via the locking member first and second portions such that relative rotation between the coupling member and compression nut is limited without deflection of the opposed threaded internal surfaces relative to each other.
Some methods further include deflecting the opposed threaded internal surfaces relative to each other by threadingly engaging the compression nut with the coupling member. In some methods the opposed threaded internal surfaces are deflected from each other a distance less than a height of threads along the threaded internal surfaces.
Disclosed are bone stabilization assemblies for use in skeletal systems. In one aspect, a bone stabilizer assembly includes a fixation element, a coupling element, a saddle, a compression nut, and retention means for retaining the saddle in the coupling element in a floating configuration that permits a predetermined amount of movement between the saddle and the coupling element. The fixation element is adapted to engage a bone and has a head portion and shank portion. The coupling element has an internal bore sized to receive the shank portion of the fixation element and a seat adapted to support the head portion of the fixation element. The coupling element is also adapted to receive a stabilizer rod. The saddle is movably mounted in the coupling element below the stabilizer rod when the stabilizer rod is in the coupling element. The compression nut is engagable with the coupling element. The compression nut is adapted to rotatingly move distally into the coupling element to translate a force to the head portion through the rod and the saddle such that the head portion is forced against the seat of the coupling element to prevent relative movement between the fixation element and the coupling element.
In another aspect, a bone stabilizer assembly includes a fixation element, a coupling element, and a saddle. The fixation element is adapted to engage a bone and has a head portion and shank portion. The coupling element has an internal bore sized to receive the shank portion of the fixation element and a seat adapted to support the head portion of the fixation element. The coupling element further includes a pair of opposed walls separated by a stabilizer rod-receiving channel. Inner surfaces of the opposed walls include inner threads for mating with a compression nut and opposing indentations located below the inner threads. The saddle is movably mounted in the coupling element below the stabilizer rod when the stabilizer rod is in the coupling element. The saddle includes a pair of opposed walls separated by a rod-receiving region. Outer surfaces of the opposed walls include opposing protrusions that extend laterally from the walls. The protrusions are adapted to engage the opposing indentations in the opposed walls of the coupling element so as to retain the saddle within the coupling element when the stabilizer rod is disengaged from the coupling element.
In another aspect, a bone stabilizer assembly includes a coupling element and a compression nut. The coupling element includes a plurality of wall sections defining a longitudinal bore. The coupling element also includes a transverse channel substantially perpendicular to the bore. The compression nut includes a substantially cylindrical engagement portion having a longitudinal axis. A thread is formed on the engagement portion so that the engagement portion is adapted to be threadedly engaged within the bore to the wall sections. The thread has a profile that has a rotation stiffening component and an anti-splay component. The rotation stiffening component and the anti-splay component are integrated.
In another aspect, a bone stabilizer assembly includes a coupling element, and a compression nut. The coupling element includes a plurality of wall sections defining a longitudinal bore and a transverse channel substantially perpendicular to the bore. The compression nut includes a substantially cylindrical engagement portion having a longitudinal axis and a thread formed on the engagement portion so that the engagement portion is adapted to be threadedly engaged within the bore to the wall sections. The thread is sloped in a distal direction from a root of the thread to a crest of the thread.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.